diff --git a/skimage/transform/_hough_transform.pyx b/skimage/transform/_hough_transform.pyx
index e0c004a3..97ff720b 100644
--- a/skimage/transform/_hough_transform.pyx
+++ b/skimage/transform/_hough_transform.pyx
@@ -20,8 +20,8 @@ cdef inline Py_ssize_t round(double r):
     return <Py_ssize_t>((r + 0.5) if (r > 0.0) else (r - 0.5))
 
 
-def _hough_circle(cnp.ndarray img, \
-                  cnp.ndarray[ndim=1, dtype=cnp.intp_t] radius, \
+def _hough_circle(cnp.ndarray img,
+                  cnp.ndarray[ndim=1, dtype=cnp.intp_t] radius,
                   char normalize=True):
     """Perform a circular Hough transform.